Carbon nanotubes-bridged-fumed silica as an effective binary nanofillers for reinforcement of silicone elastomers

Abstract The incorporation of nanofillers into polymeric matrix has been proven to be an effective route to reinforce their mechanical properties, and the usage of binary fillers that combines the advantages of the two fillers could lead to further property enhancement. In this work, binary nanofillers consist of multi-walled carbon nanotubes (MWCNTs)-bridged fumed silica (FSiO2) were synthesized for the first time by Pt coupling reaction of methyldiethoxysilane (MDES) modified MWCNTs and triethoxyvinylsilane (TEVS) functionized SiO2, in which MDES modified MWCNTs was synthesized by reacting OH-functionized MWCNTs with MDES, while TEVS-FSiO2 was obtained by reacting fume silica with TEVS. The binary MWCNTs-bridged-FSiO2 was introduced into liquid silicone rubber (LSR) for mechanical reinforcement. It is shown that the interfacial interaction between binary fillers and LSR matrix is significantly enhanced due to the chemical bridging as well as the excess TEVS molecules on SiO2, and the Young's modulus, tensile strength and tear strength of the LSR could be increased by 64%, 29% and 52%, respectively, with incorporation of only 0.25 phr of MWCNTs for the binary fillers. The observed mechanical enhancement could be attributed to good interfacial interaction between the fillers and LSR due to the existence of SiO2 (with excess matrix compatible molecules) on the surface of MWCNTs, which facilitate the filler dispersion in LSR matrix and the promote stress transfer from matrix to MWCNTs, as well as the advantages of extremely high aspect ratio and excellent mechanical strength of MWCNTs.